Titanium-tantalum high-speed steel



United States Patent 3 295 964 TiTANrUM-TANTAIZUr i HIGH-SPEED STEEL Masao Kondo, Masuxni Ohsawa, and Tom Arai, Tovamawell as to form carbides of Ti and Ta. However, the carbon content should be varied in accordance with amounts of Ti and Ta. Even when the quantity of Ti+Ta is equal to 0.5%, at least 0.6% is necessary from Fig 5331 23 g fi g g gs gi ii gg i g g gg 5 heat-treatment point of View. In the case wherein quan- No Dravi ing. ileii Niar. 16, 1966, S51. 1&0. 53 5656 i of Ti+Ta is i when the carbon F Claims Priority applicafign Japan, Dem 23 1961, is above 5%, their carbides become coarse and brittle, so

36/471,536 that quantity of carbon should be 0.6 to 5%. For exam- 4 Cl i (C1, 75 123) ple, the necessary carbon content is selected to be 0.4% 10 with respect to 1% of Ti and 1% with respect to 1% of This application is a continuation-in-part of prior ap- Ta. plication Ser. No. 234,233 filed on October 30, 1962, now The nature and details of the invention will be more abandoned, in the same of Masao Kondo et al., and enclearly apparent by reference to the following description titled Titanium-Tantalum High-Speed Steel. of a few representative embodiments of the invention.

This invention relates to high-speed steels, and more The compositions of steels containing both titanium particularly it relates to new high-speed steels containing and tantalum, that is, the steels of this invention Mo, Ti, carbide with titanium and tantalum as its principal con- Ta (A) and Mo, Ti, Ta (B) and the compositions of stituents. molybdenum-titanium high-speed steel Mo, Ti, molybde- High-speed steels of conventional type, quenched and mum-cobalt high-speeed steel M and molybdenum hightempered, have heretofore contained almost entirely only speed steel M which are considered here for the purpose two kinds of carbide, One i the M 0 type a bide with of comparison and reference, are as shown in the Table 1. tungsten and molybdenum as its principal components and When the Steels and of this invention Were Silhanother i an MC type a bid ith n di as it p injected to heat treatment under exactly the same conditions cipal component, these carbides participating eifectively as those p y Ordinary high-Speed Steels, hard in the cutting performance. nesses after quenching and tempering of HRC 65 or high- It is an essential object of the present invention to pror Were obtained, and better results than M36 steel in the vide a group of new titanium-tantalum high-speed steels P p y of withstanding tempering were Obtained which have, in addition to good heat-withstanding propcutting tests were Carried hilt 011 Square 011terty, good chipping-resistant property and excellent cutting g tools made of the Steels of this invention and P characteristic. pared by heating for 3 minutes at 1,250 degrees C. and The present invention relatesto a titanium-tantulum Oil quenching and tempering twice in One hour at 550 high speed steel consisting essentially of up to 25% tungdegrees to Produce a hardness of HRC n sten, up to 20% molybde um, up t 10% h i up on other cutting tools made of steels to be compared with to 10% vanadium, 0.2 t 6% tit i 03 to 6% tantuthe steels of this invention, the said other cutting tools lum, the total percentage of the titanium and tantulum being Subjected to their respectively Optimum heat treatcontents being about 0.5 to 10% and the ratio of the timerit, and Comparison of test Cutting performances of tanium content to the tantulum content being 120.5 to 1 :2, these Cutting toeis was madesaid the percentages being weight percentages and the re- The method of these tests in all cases was the Cutting i d component b i i operation commonly called facing, and the test conditions The above-mentioned high speed steel according to this were as follows: I invention has been proposed as a result of various experi- Condition 1 was high-Speed cutting of a d ma i l ments of the inventors of this invention. The amounts of (Chromium-molybdenum Steel, Japan Industrial Standard various constituents of the steel according to this inven- Designation SCM 5, Containing tion are based on the following reasons. That is, when 035% Si, (mo-055% M11, 0-030% hiaX- 0-030% a Ta/Ti is below 0.5, toughness of the high speed steel 45 S, and and having a becomes inferior and when Ta/Ti is above 2, high speed Brinell hardness of with heat nce COH- cutting ability of the high speed steel become low. sideied as the Principal measure for Comparison- On the other hand; Condition 2 was low-speed cutting, similarly of a hard When amount of tungsten is above 25%, toughness f material, with wear resistance considered as the principal the product becomes low, when amount of molybdenum measure for comparisonis above 20%, cutting ability of the product becomes low; Condition 3 was high-Speed cutting of a workpiece when quantity of chromium is above 10%, heat treated which was Provided With a groove 0 a diameter so as hardness of the product decreases, and when quantity of to impart impact to the cutting g of the cutting tool, vanadium is above 10%, hard carbide becomes large, thus and which was made of relatively soft material causing difiiculty of the working and decrease of toughsteel for machine construction, Japanese Industrial Standness of the product. ards Designation S 45 C, containing 0.400.50% carbon In the production of the high speed steel according to and having a Brinell hardness of 167 to 229), resistance this invention, carbon content should be an excess quanagainst chipping being considered as the principal meastity sufiicient to form carbides of W, Mo, Cr and V as ure for comparison.

TABLE 1 Kind of Steel Designation C W Mo Cr V Co Ti Ta Symbol Stgelqofqthis invention containing 0.6% Ti, MoTiTa (A). 1.33 10. 40 4. 53 4. 28 2.11 0.60 0.74

Steel of this invention containing 1.2% Ti, MoTiTa (B) 1. 55 13.00 4.13 3.82 1.87 1.18 1 44 1.4% Ta.

Molybdenum-titanium high-speed stee1- MoTi 1. 72 8. 73 5. 2 4, 20 2 0 00 Molybdenum-cobalt high-speed teel M36. 0.80 6 5 4 2 Molybdenum high-speed steel M2 0.85 6 5 4 2 As a criterion of performance, the width of wear of the flank surface after cutting or the cut-ting speed at the time of termination of the life of the tool was meas- As indicaed in Table 2, the steel alloy MoTi containing the carbide which has Ti as its principal constituent has the greatest heat resistance, but exhibits somewhat low resistance against chipping.

The steel alloy MoTiTa containing the carbide which has Ti and Ta as its principal constituents has heat resistance of a magnitude which depends on the quantity of the said carbide and is equal to or greater than that of the steel M but in resistance against chipping, the steel MoTiTa is superior to the steel MoTi and almost equal to M The steel MoTiT a is definitely superior to the steel M in wear resistance.

The high speed steel, the carbide containing Ti and Ta as its principal constituents prepared by adding Ti and Ta and a quantity of carbon sufficient for forming carbide with the said Ti and Ta, has greater chipping resistance than a steel containing a carbide having Ti as its principal constituent, has heat resistance and chipping resistance which are equal or superior to those of cobalt high-speed steel, and is superior to cobalt high-speed steel in wear resistance.

Accordingly, if a high-speed steel containing carbide which has Ti and Ta as its principal constituents is used as a tool material for high-speed cutting and cut-ting of hard work materials, the cutting tools made of such a material will exhibit excellent cutting performance.

This excellent cutting performance exhibited by the steel according to this invention may be thought to be due to the extreme hardness of the carbide having Ti and Ta as its principal constituents and due to its superior toughness as compared to that of a carbide having Ti as its principal constituent.

High-speed steels in which small quantities of Ti and Ta were added with the aim of efiecting deoxidation, denitrification, or refinement of structure have heretofore been used on a trial basis. In contrast, however, the highspeed steel of the present invention contains, in addition to M c carbide and VC carbide, carbide having Ti and Ta as its principal constituents, wherefore the significance of these additives is exhibited for the first time, and it is absolutely necessary for the steel of this invention to contain, together with Ti and Ta, a quantity of carbon which is sutficient for combining with Ti and Ta. Therefore,

the high-speed steel of the present invention difiFers in essence from the above-mentioned steels used heretofore.

The high-speed steel of this invention may be made by adding titanium, tantalum, and other metallic elements and carbon as separate mother alloys and casting the same, but when it is made by a quick heating and cooling method such as build-up welding with a solid solution pow-er consisting of TiC and Tac, or these carbides together with other kinds of carbides, as the starting material, the carbide With Ti and Ta as its principal constituents is finely distributed, and a high-speed steel having excellent mechanical properties and cutting performance is easily produced.

It is a requisite of the steel of the present invention that it contain both titanium and tantulum, the lack of either, of these alloying elements causing the steel to have inadequate properties. 1

As a result of experimental research, it has been found that the chemical compositions stated in the appended claims are suitable for the high-speed steel according to the invention.

What we claim is:

1. A titanium-tantulum high speed steel consisting essentially of up to 25% tungsten, up to 20% molybdenum, up to 10% chromium, up to 10% vanadium, 0.2 to 6% titanium, 0.3 to 6% tantulum, 0.6 to 5% carbon and the balance essentially iron, the total percentage of the titanium and tantulum contents being about 0.5 to 10% and the ratio of the titanium content to the tantulum content being 120.5 to 1:2, all said percenages being by weight.

2. A titanium-tantulum high speed steel according to claim 1, in which the carbon content-of the high speed steel is a quantity sufficient to form carbides of said tungsten, molybdenum, chromium and vanadium and includes an excess beyond an amount required to form said carbides, said excess being suflicient to form carbides of said titanium and said tantalum.

3. A titanium-tantulum high-speed steel according to claim 2, in which the titanium content is about 0.6 to 1.18% and the tantulum content is about 0.74 to 1.44%.

4. A titanium-tantulum high-speed steel according to claim 3, in which the tungsten content is about 10.4 to 13%, the molybdenum content is about 4.13 to 4.53%, the vanadium content is about 1.87 to 2.11%, and the carbon content is about 1.33 to 1.55%.

References Cited by the Examiner UNITED STATES PATENTS 1,645,213 10/1927 Armstrong 123 X 2,576,229 11/1951 Krainer 75-126 2,665,205 1/1954 Klaybor 75126 2,781,259 2/1957 Roberts 75126 3,044,872 7/1962 Hays et al. 75-126 3,183,127 5/1965 Gregory et a1 75-126 DAVID L. RECK, Primary Examiner. l. WEINSTEIN, Assistant Examiner, 

1. A TITANIUM-TANTULUM HIGH SPEED STEEL CONSISTING ESSENTIALLY OF UP TO 25% TUNGSTEN, UP TO 20% MOLYBDENUM, UP TO 10% CHROMIUM, UP TO 10% VANADIUM, 0.2 TO 6% TITANIUM, 0.3 TO 6% TANTULUM, 0.6 TO 5% CARBON AND THE BALANCE ESSENTIALLY IRON, THE TOTAL PERCENTAGE OF THE TITANIUM AND TANTULUM CONTENTS BEING ABOUT 0.5 TO 10% AND THE RATIO OF THE TITANIUM CONTENT TO THE TANTULUM CONTENT BEING 1:0.5 TO 1:2, ALL SAID PERCENAGES BEING BY WEIGHT. 